After softening the shock of “The Hangover” by repeating its vulgar jokes in the sequel, “The Hangover Part III” returns surprise to the franchise. Some folks won’t be happy about that.

The surprise is that this trilogy concludes with a movie in which action often speaks louder than comedy. It isn’t as consistently, convulsively funny as “The Hangover,” or apparently intended to be. If the original romp felt like a throwback to 1980s frat house slapstick, “The Hangover Part III” is more like “Beverly Hills Cop,” a generic crime flick improved by comical touches that shouldn’t fit the proceedings.

At the center of the crime is Mr. Chow (Ken Jeong), the effeminate cokehead who stole scenes in parts one and two but shouldn’t be asked to carry an entire movie. Part three begins with Chow pulling a Shawshank escape from a Bangkok prison, the first step in his scheme to recover a fortune in stolen gold bullion. Everything gets explained in full by the gangster Marshall (John Goodman), part of the script’s reliance upon bulky exposition.

Meanwhile, runt-of-the-Wolfpack Alan (Zach Galifianakis) has gone off his meds, showing behavior more erratic than usual. His personality disorder leads to two deaths in the opening minutes, including this movie’s running joke of animal cruelty. Yes, it’s funny seeing a giraffe decapitated by a freeway overpass because that’s so outrageously improbable; what happens later to dogs and roosters is less so.

Alan’s family believes an intervention is in order, and the remaining Wolfpack members are enlisted to take him to the sanitarium. They don’t make it, thanks to Marshall’s intrusion, knowing Alan and Chow are pen pals. The dullest Wolf (Justin Bartha) is taken hostage until Alan, Phil (Bradley Cooper) and Stu (Ed Helms) bring Chow to the mobster.

The trail leads to Tijuana and eventually back to Las Vegas, where the action flick conventions — car chase, parachute escape, blazing guns — really kick in. Galifianakis plays comfortably dumb throughout, but Cooper and Helms have little to work with besides exasperation. Their characters worked out their kinkiness through two movies, leaving a pair of respectably married guys. The Wolfpack doesn’t even get drunk or stoned in this movie until the end credits — which aren’t based on surreptitious photos like before — so “Hangover” is a misleading title.

There’s a nicely weird appearance by Melissa McCarthy as a pawn shop clerk with heavily mascara-ed eyes for Alan, her brief scenes with Galifianakis offering the gonzo humor fans expect, and the movie needs more of. Jeong’s mania has its moments. But for much of “The Hangover Part III,” we’re left wondering where the guffaws went and why these formerly wild and crazy guys aren’t riding off into the sunrise.